doc: add AnnaMag to collaborators

PR-URL: nodejs/node#12414
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Alexey Orlenko <eaglexrlnk@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>

Author: AnnaMag

README.md

@@ -229,6 +229,8 @@ more information about the governance of the Node.js project, see
 **Andras** <andras@kinvey.com>
 * [AndreasMadsen](https://github.com/AndreasMadsen) -
 **Andreas Madsen** <amwebdk@gmail.com> (he/him)
+* [AnnaMag](https://github.com/AnnaMag) -
+**Anna M. Kedzierska** <anna.m.kedzierska@gmail.com>
 * [aqrln](https://github.com/aqrln) -
 **Alexey Orlenko** <eaglexrlnk@gmail.com> (he/him)
 * [bengl](https://github.com/bengl) -